Fast reactor and fast reactor reflector assembly

Abstract

A fast reactor performing reflector control to control reactivity of the core by moving a neutron reflector in the vertical direction, including: a core fuel assembly; a neutron absorption assembly in the middle of the core fuel assembly; a reflector assembly at the circumference of the core fuel assembly; plural inner neutron shields at the circumference of the reflector assembly; a cylindrical core barrel surrounding entirety of the plural neutron shields; and a drive mechanism controlling the reflector. The reflector assembly includes: a reflector element that reflects neutrons from the core fuel assembly towards the core; a cavity section, arranged thereabove, that permits leakage of neutrons to outside the core; a linkage mechanism that links the reflector element and the cavity section; a guide tube that defines a space for removal/insertion of these; and a connecting section that connects the drive mechanism and the cavity section.

1 . A fast reactor in which reflector control is performed to control a core reactivity, by adjusting neutron leakage from a core by moving in a vertical direction a neutron reflector that is arranged radially outside said core, which is bathed in liquid metal coolant, said fast reactor comprising:
 a plurality of core fuel assemblies that move in mutually parallel fashion in a vertical direction;   a neutron absorption assembly that moves in said vertical direction, provided in a middle in a horizontal direction of said plurality of core fuel assemblies;   a plurality of reflector assemblies moving in said vertical direction, arranged in a horizontal peripheral region of said core fuel assemblies;   a plurality of neutron shields arranged in a horizontal peripheral region of said core fuel assemblies;   a cylindrical core barrel provided surrounding an entirety of said plurality of neutron shields in said horizontal direction; and   a drive mechanism for said reflector control,   wherein said reflector assemblies comprise:
 a reflector element that reflects neutrons flowing out from said core fuel assembly towards said core; 
 a hollow cavity section arranged perpendicularly above said reflector element for permitting leakage of neutrons flowing out from said core fuel assembly towards outside said core; 
 a linkage mechanism that links said reflector elements and said cavity sections; 
 a guide tube defining a space for insertion/removal of said reflector element, said cavity section and said linkage mechanism; and 
 a connecting section that connects said drive mechanism and said cavity section, 
   wherein said reflector element and said cavity section are moved vertically through an interior of said guide tube by said drive mechanism.   
     
     
         2 . The fast reactor according to  claim 1 ,
 wherein said guide tube is equipped with an aperture that permits passage of neutrons in its side face.   
     
     
         3 . The fast reactor according to  claim 1 ,
 wherein in said linkage mechanism, said reflector element and said cavity section are fitted together and a fitting section of them is secured by means of bolts.   
     
     
         4 . The fast reactor according to  claim 1 ,
 wherein horizontal cross-sectional external shapes of a plurality of core constituent elements surrounded by said core barrel and comprising said core fuel assembly, said neutron absorption assembly, said reflector assembly and said neutron shield are regular hexagonal shapes of same dimensions, opposite faces of mutually adjacent said constituent elements being parallel, and   wherein a horizontal cross-section of said reflector element and said cavity section accommodated in said space within said guide tube is circular.   
     
     
         5 . The fast reactor according to  claim 1 ,
 wherein said horizontal cross-sectional external shapes of a plurality of core constituent elements surrounded by said core barrel and comprising said core fuel assembly, said neutron absorption assembly, said reflector assembly and said neutron shield are regular hexagonal shapes of same dimensions, opposite faces of mutually adjacent said constituent elements being parallel, and   wherein said horizontal cross-section of said reflector element and said cavity section accommodated in said space within said guide tube is regular hexagonal.   
     
     
         6 . The fast reactor according to  claim 1 ,
 wherein said connecting section has a suspension plate and said horizontal cross-section of said reflector element, and said cavity section and said suspension plate accommodated in said space within said guide tube are of regular hexagonal shape.   
     
     
         7 . The fast reactor according to  claim 1 ,
 wherein a material of said guide tube includes at least one of stainless steel, aluminum, or zirconium.   
     
     
         8 . The fast reactor according to  claim 1 ,
 wherein said connecting section is provided with a suspension plate and said reflector element is directly coupled with said suspension plate.   
     
     
         9 . The fast reactor according to  claim 1 ,
 wherein said reflector element is provided with a flow path aperture passing therethrough in said perpendicular direction.   
     
     
         10 . A reflector-controlled type fast reactor reflector assembly, in which a core reactivity is controlled by adjusting neutron leakage from a core by moving in a vertical direction a neutron reflector that is arranged radially outside said core, which is bathed in liquid metal coolant, said reflector assembly comprising:
 a reflector element that reflects neutrons flowing out from said core fuel assembly towards said core;   a hollow cavity section arranged perpendicularly above said reflector element for permitting leakage of neutrons flowing out from said core fuel assembly towards outside said core;   a linkage mechanism that links said reflector element and said cavity section;   a guide tube defining a space for insertion/removal of said reflector element, said cavity section and said linkage mechanism; and   a connecting section that connects said drive mechanism and said cavity sections,   wherein said reflector element and said cavity section are moved vertically through an interior of said guide tube by said drive mechanism.   
     
     
         11 . The fast reactor according to  claim 2 ,
 wherein in said linkage mechanism, said reflector element and said cavity section are fitted together and a fitting section of them is secured by means of bolts.   
     
     
         12 . The fast reactor according to  claim 2 ,
 wherein horizontal cross-sectional external shapes of a plurality of core constituent elements surrounded by said core barrel and comprising said core fuel assembly, said neutron absorption assembly, said reflector assembly and said neutron shield are regular hexagonal shapes of same dimensions, opposite faces of mutually adjacent said constituent elements being parallel, and   wherein a horizontal cross-section of said reflector element and said cavity section accommodated in said space within said guide tube is circular.   
     
     
         13 . The fast reactor according to  claim 2 ,
 wherein said horizontal cross-sectional external shapes of a plurality of core constituent elements surrounded by said core barrel and comprising said core fuel assembly, said neutron absorption assembly, said reflector assembly and said neutron shield are regular hexagonal shapes of same dimensions, opposite faces of mutually adjacent said constituent elements being parallel, and   wherein said horizontal cross-section of said reflector element and said cavity section accommodated in said space within said guide tube is regular hexagonal.   
     
     
         14 . The fast reactor according to  claim 2 ,
 wherein said connecting section has a suspension plate and said horizontal cross-section of said reflector element, and said cavity section and said suspension plate accommodated in said space within said guide tube are of regular hexagonal shape.   
     
     
         15 . The fast reactor according to  claim 2 ,
 wherein a material of said guide tube includes at least one of stainless steel, aluminum, or zirconium.   
     
     
         16 . The fast reactor according to  claim 2 ,
 wherein said connecting section is provided with a suspension plate and said reflector element is directly coupled with said suspension plate.   
     
     
         17 . The fast reactor according to  claim 2 ,
 wherein said reflector element is provided with a flow path aperture passing therethrough in said perpendicular direction.